The two major goals of this project are (1) to characterize active ion transport by the Lepidopteran midgut, isolate the transporting membranes, purify their constituent proteins and phospholipids and reconstitute the system in functional liposomes and (2) to compare the transport and phosphorylating properties of the midgut K ion transporting system with those of other electrogenic systems such as the phosphorylating membranes of mitochondria. Currently we are studying optimal conditions for K ion transport in three midgut regions, trying to identify and isolate a blood borne factor which regulates the K ion pump via cycle nucleotides, preparing for an electron microprobe analysis of ionic concentrations in several midgut compartments, studying the spatial relationship of portasomes to electrochemical gradients during transport and attempting to demonstrate synthesis of ATP by K ion pump reversal. We are also trying to isolate plasma membrane fractions.